vino, ossigeno, controllo, impianti, tecnica e scienza

330 members who each year contribute 6.500 tons of grapes, of which approximately 5.000 are Barbera: these are the figures of the Cooperative Winery Barbera dei Sei Castelli di Agliano Terme, in the heart of the most prestigious denomination for the Piedmont variety, the Barbera d’Asti DOCG.

Ever attentive to the most modern vinification and refinement techniques, in 2013 the Barbera dei Sei Castelli cellar adopted a Parsec micro-oxygenation system adept in ensuring proper management of oxygen in macro- and micro-oxygenation in the majority of tanks distributed throughout various winemaking and storage areas. The structure is comprised of 7 basic multiple periphery units for micro-oxygenation (with the possibility also of macro-oxygenation and single-dose applications) of 24 tanks from 250 to 1500 hl and 4 units of multi-output macro-oxygenation (with macro-oxygenation and single-dose provision) serving 20 tanks with a capacity ranging from 500 to 1000 hl.

Macro- and micro-oxygenation are thus utilised in the necessary doses throughout entire life of the wine, from fermentation to refinement, as recounted by Enzo Gerbi, Oenologist and Technical Director of the Cantina, speaking about his experience with micro-oxygenation of the Barbera and other grapes processed within the winery.

How long have you been utilising macro- and micro-oxygenation?

E.G. My first encounter with micro-oxygenation dates back to around 10 years ago when I initially experimented with a micro-oxygenation system on Barbera in a small mono-tank. Following this, we continued to apply the oxygen dosages, still limited to Barbera d’Asti and always with small mono-vat dispensers that allowed for the effectuation of macro-oxygenation in vinification and micro-oxygenation further on in the course of storage, until we became equipped with a centralised system for a much more widespread use of oxygenation in the 2013 vintage, both in terms of macro- and micro-oxygenation.

What were your experiences and, on the basis of these, how has the relationship with oxygen and your wines evolved?

E.G.We commenced with the application of micro-oxygenation initially in a very reduced means, with very few tanks and always in the post-racking phase on a Barbera with an important structure both in polyphenolic and alcoholic terms. We subsequently implemented the use of macro throughout the fermentation -even utilising few units rotated on the set-up to various tanks each day- before turning to micro-oxygenation post-racking through to the beginning of malolactic fermentation. In these instances, I have always noticed better fermentation being effectuated and greater olfactory cleanliness and gustatory precision, associated with a better colour fixation. All this led me to installing the Parsec system so as to better manage oxygen throughout each part of the cellar and for each necessity.

In particular, I was driven to use macro-oxygenation throughout the fermentation of white wines (for us being Cortese and Chardonnay) and local red wines being Grignolino and Dolcetto.

During the first harvest, that of 2013, I commenced with dosages with a single 2/3 mg/l dose and, little by little, moved on to certain experiments with dosages of 2/3 mg/l/day of macro-oxygenation for a duration of 2 days. The results were a sharp olfactory cleanliness in the Cortese, no loss of perfumes and an optimum preservability of the wine throughout the vintage. In addition to the oxygen management, it has permitted me to completely eliminate the use of copper sulphate in winemaking.

As such, with the 2014 vintage and at this point on all the white wines I effectuated continuous macro-oxygenation with dosages ranging from 4 to 2 mg/l/day for 2/4 days, in accordance with the olfactory sensors of the moment, starting from the third day of fermentation, with the result of a regular fermentive process through to the complete fermentation of the sugars and a remarkable olfactory cleanliness.

In regards to the Barbera, our processing protocol foresees a dosage of macro-oxygenation during fermentation and maceration of 4-7 mg/l/day until the end of fermentation, before successively moving on to the racking (usually after 2-3 days) to effectuate a macro of approximately 2-3 mg/l/day for 4-5 days and then passing to the micro of 2 mg/l/month that normally, after several days and following a tasting check, is reduced to 1 mg/l/month until the exhastion of 50% of the malic acid.

After pouring off at the end of the malolactic fermentation, the micro-oxygenation continues at a dosage of 1 mg/l/month whilstever the temperatures allows it (unfortunately in areas of the cellar, it is still problematic to maintain the wines at an ideal temperature for micro-oxygenation).

What control parameters are utilised in the follow-up of the micro-oxygenation process?

E.G.Normally, our checks are based on the analytical evaluation of the index of total polyphenols, anthocyanins, the tannin/anthocyanin correlation, the state of the combination of anthocyanins with the dTat% index, the ethanale content and the management of free sulphur dioxide and, naturally, a great deal of attention to the tasting.

What challenges have been resolved with the use of micro-oxygenation?

E.G.I would not say that it has allowed me to resolve great difficulties in so much as having improved that which is possible to obtain. From an operational point of view it has allowed me to eliminate air-exposed pumpovers, with greater rationalisation of time spent working and of personnel. This has then allowed us to anticipate the commencement of the malolactic fermentation, particularly in wines with high alcohol and polyphenolic potential where I have, in fact, observed that the vats with micro-oxygenation normally commence their malolactic fermentation earlier than the same wine in simple tanks.

What qualitative results have you been able to achieve with the application of micro-oxygenation?

E.G.Definitely a greater olfactory clarity for both red and white wines, as well as a better obtainment of colour that I consider the greatest advantage garnered with Barbera.

Managing alcoholic fermentation

Alcoholic fermentation is the key process in the transformation of grapes into wine: for each molecule of the sugars -glucose or fructose- two molecules of ethanol and two of carbon dioxide are produced.

C6H12O6 → 2 CH3CH2OH + 2 CO2

The protagonist of this transformation (in which many other compounds essential to the quality of the wines are also produced as by-products of the fermentation process or by other metabolic means) is the Saccharomyces cerevisiae yeast.

A fermentation is considered correct when the population of the yeasts, both those indigenous present in the must or, better yet, those inoculated from a selected culture, quickly prevail upon the undesired micro-organisms (such as bacteria, for example), having a positive commencement and proceeding correctly in the consumption of the sugars up until the point of their total depletion.

For their metabolism, yeasts require (naturally, besides sugars) nitrogenous substances (capable of assimilating both inorganic nitrogen in the form of ammonium ions and amino acids), growth factors (the vitamins and mineral salts that function as cofactors in many enzymatic activities) and survival factors (saturated and unsaturated fatty acids and sterols that form the cellular membrane guaranteeing their functionality).

The principal risk, when the lack of some of these elements provokes stress to the yeasts, is that they cease to consume sugars and the cells progressively die. In these cases, one speaks of a stunted fermentation and, in the worst cases, of arrested fermentation.

In the cellar, wine producers and oenologists are equipped with certain instruments to manage the needs of the yeasts and avoid risks: the nitrogenous nutrients (ammonium salts and derivatives of the yeast that are rich in amino acids and membrane lipids), oxygen (necessary for the synthesis of unsaturated fatty acids and sterols) and temperature (which must be maintained within a range, typical to each strain, optimal for the development of the yeast).

Control above all else

But how should these instruments be utilised? For the correct management of the fermentation and the health status of the yeasts, control is the basis of everything and needs to provide a respond to the questions: How is my fermentation proceeding? How are my yeasts?

The most common fermentation verification in the cellar is the indirect measurement of the consumption of sugars determined by the densimeter: passing from a sugar solution to a hydroalcoholic solution, the must progressively diminishes in density, with such decreasing being proportional to the reduction of sugars in the solution.

The density expressed on a different scales (Babo, Oeschle, etc.) is measured in a sample, considered representative of the mass in fermentation (assuming there is homogeneity within a vat), once or, less commonly, twice daily.

The research carried out especially in the two most active schools in the study of alcoholic fermentation management, that of Jean Marie Sablayrolles at the INRA in Montpellier in France and of Linda Bisson at the University of California, Davis, since the end of the 1990s have evidenced that the parameter best describing the characteristics of quality and the critical points of the fermentation process is the instantaneous velocity of fermentation.

The fermentation speed has a typical evolution for each phase of the growth curve for the yeast population (start-up, exponential growth, stationary and death phases). With a typical (and optimal) curvature in the initial phase, it increases until reaching a maximum peak of approximately 1/4 of the consumption of the sugars, only to then diminish whilst remaining constant before decreasing rapidly upon the complete exhaustion of the sugars.

Certain typical points on the fermentation velocity curve can provide fundamental informations for the evaluation of the fermentation quality and for its correct management: the maximum speed obtained at the end of the exponential phase, the time employed to reach such a speed and the slope of the fermentation velocity curve at the point of transition in the phase from maximum speed to the stationary phase.

The studies undertaken by Sablayrolles have also defined that the best period for the addition of nitrogenous nutrients and for the oxygenations necessary for the synthesis of the lipid compounds of the membrane ranges from the moment of maximum velocity (at around 1/4 of the alcoholic fermentation) to mid-fermentation.

When the fermentation velocity diminishes in an anomalous mode, above all after having reached its maximum peak and during the stationary phase, deviating from this typical evolution, it may be that the yeast is up against a situation of stress and is not longer able (due to the lack of nitrogenous substances or of a state of inefficiency of the cellular membrane) to assimilate and transform the sugars.

Monitoring carried out at daily intervals, such as that executed with the densimetric measurement, is often unable to detect neither the moment in which the maximum peak of velocity is achieved (and thus the best moment for technological interventions of nutrition and oxygenation) nor its level and is not even able to intervene in a timely manner in the event of a slowdown.

Following a study that commenced in 2004 in collaboration with the The Department of Agricultural and Forest Economics, Engineering, Sciences and Technologies of the University of Florence, and stemming from the necessity of measuring parameters such as the fermentation velocity and other critical points with accuracy and promptness, Parsec has developed a system suitable for the continuous monitoring of the fermentation progress, through the direct measurement of one of the products of the transformation of sugars, CO2.

The ADCF system (Dynamic Analysis of Fermentation Kinetics) provides a continuous and very precise measurement of that which is occurring in the entire fermentation mass, measuring the quantity of CO2 produced by the yeasts, without being influenced by the effect of the sampling.

To render an idea of the volumes of CO2 that should be measured, we can consider that the fermentation of a must containing 220 g/l of sugar (about 13° V/V in potential alcohol), produces about 55 litres of CO2 per litre of must. This is a very high volume, if taking into account that only 1% is kept in dissolved form within the liquid, while all the rest will be released externally.

With the volumes of gas of this type, one is led to believe that the measuring should not be difficult. Actually, this is not the case at all. The volumes of CO2 that are produced in the fermentation are not liberated at a constant velocity and a reliable system necessitates an identical precision in the detection of gas produced at each interval (from the lowest to the most elevated) and throughout the entire period in which the process should be monitored. A system able to oversee with precision only the initial phase when the volumes produced are elevated, for example, is not useful in that it does not allow for the detection of any eventual slowdowns in the final and most critical phases for the completion of the sugar consumption.

The existing ADCF system was perfected after a thorough evaluation of the sensors available on the market and the gas flow measurement systems, being reliable and accurate yet efficient only in a limited CO2 range, unable to guarantee a uniform accuracy and reliability throughout the entire interval in which it is necessary to measure the fermentation progress. ADCF rather offers a closed system applicable to any type of tank (whereby equipped with a hatch) that keep the vat in marginal overpressure, measuring even the slightest variations in pressure and temperature owing to the production of CO2.

The fermentation velocity of each tank can be monitored in real-time with ADCF. Data management via the integrated Saen5000 system not only permits the remote archiving and visualisation of the curvature, but also to communicate and interact with the fermentation parameters together with other functions managed by the system, from the temperature control to the oxygenation or remontage operations.

A cellar today is not merely a place of production. Its design must respond to various requirements, such as its integration with the landscape, the necessity for guest reception and the presentation of the image that the producer wishes to give of itself, not only through the quality of the wines, but also through the values based on its relationship with the areas, the territory and the environment.

All this must be without losing sight of the functionality and technological requirements of the oenological process.

The design of the new cellar of the “Le Palaie” farm is the realisation of an idea had by Angelo Nino Caponi, for his Montecchio estate in the municipality of Peccioli, Val d’Era, an emerging wine region in the tuscan province of Pisa.

The designers of the structure, Studio Casati di Peccioli, created the basement-level cellar within a hill overlooking the vineyard of Montecchio, taking advantage of the natural morphology of the terrain that presents as a large trapezoidal expanse unfolding towards the valley.

The areas of the winery are distributed over two floors, with the lower level housing the barrel room in the innermost basement area to the north, and the partially below-ground vinification areas to the south.

On the upper level are situated rather the premises for the offices, the reception areas and the tasting room. The two floors are connected by an internal staircase representing an architectural and artistic element, with glass walls providing visitors with a view of the cellar areas from up above.

The cellar was designed with the utmost attention to detail, not only in terms of its stylistic and architectural aspects, but also for its logistic and production elements, from the correct management of its energy consumption, to its lighting and workplace safety.

The cellar is fitted out with the integrated supervisory system SAEn5000, which unites in one piece of equipment all the control and management functions for the tanks and premises in a BUS network.

The tronconic steel vinification vats, equipped with manual treaders for punching down on rails and those in concrete with a new conception and form, are fitted with a multifunction system for management of the temperature (hot and cold) and micro-oxygenation.

The Parsec SAEn5000 system also permits the integrated overseeing of the aeration and climate control system of the winemaking and barrel storage areas, fitted in the niches present between barriques, with various sculptures transforming the production environment into a veritable art gallery.

barrel room

barrel room

overview of the technical zone

winemaking area

technical zone

tronconic tank in steel

concrete winemaking tanks in an innovative shape

barrel room

winemaking area

Parsec’s know-how with gases applied safely to the cellar

The management of the CO2 extraction plus the aeration of the vinification areas and barrel room have necessitated the design of an automated system equipped with diverse security features.

“The extraction of CO2 in the winemaking areas is safeguarded by four extractors equipped with ventilators positioned a few centimetres from the ground,” explains Leo Forte who oversaw the project. “The exchange of clean external air has a double modality: fresh air enters in a passive means via four vertical channels that run within the columns of the structure and which extract clean air from the roof to be inputted into the areas to enact the actioning of depressions created by ventilators for the expulsion of carbon dioxide, and in an active means from a central funnel equipped with a ventilator that diffuses the air throughout all the areas to forcibly ‘sweep out’ the carbon dioxide from below.”

“The extraction of the CO2 and the ventilation are managed automatically by a series of detectors specifically constructed by Parsec in collaboration with a leading company in gas sensor systems,” continues Forte, “that detect carbon dioxide from the fermentation at a base level of 0.5% to activate the extraction process, while activating an optical and acoustic evacuation alarm system should the CO2 exceed the level of 1%.”

Besides this automation system, in the case of its activation SAEn5000 manages in a priority manner the closure of the hinged windows positioned externally throughout the area, so as to avoid the expelling of air entering through the windows instead of the accumulated CO2, ensuring that the entire system operates in a reliable and secure manner.

The climate control of the barrel room is guaranteed by air entering from two columns positioned on the front of the cellar and, with a nod to the maritime transport activities of Caponi, visible from the outside like two ship funnels.

The fresh air is mixed with that from within the premises before being cooled or heated by two thermoventilation machines that ensure the air circulation in the two wings of the barrel room. A system of free-cooling, or “natural air-conditioning”, managed by SAEN5000 through sensors positioned in the external columns to the north, operates to ensure that the air is extracted at the time of day when the external temperature and humidity are closer to those desired and necessitated in the barrel room. In this way, it is ensured the optimisation of the functioning times of the thermal-ventilating machines that heat or cool air only in the times effectively required, with evident energy savings.

Illumination of the project in its realisation

Even the lighting of the new Nino Caponi cellar was curated by Parsec.

“Commencing with the architectural project, the selection of the most fitting points of light and illumination forms both externally and internally was necessary for the scenographic and functional aims,” recalls Leo Forte “The next step was the selection of the most suitable equipment for each application, the simulation of the lighting effect in the rendering and ultimately in the technical trials on the construction site with various daytime and nighttime illumination.”

Saen5000

The characteristic that most distinguishes the Parsec SAEn5000 system is the multilevel and multiprocessor structure. A microprocessor is dedicated to each function and is controlled hierarchically, from a single unit installed on a tank through to the personal computer from which the user manages the whole process simply and intuitively.

The Parsec system was born and developed especially for the cellar. Unique in the international technological panorama thanks to its modularity and flexibility, it also provides for the optimisation and simplification of the set-ups as a whole and thus a considerable re-dimensioning in mass and encumbrance of the equipment and its electrical cables, maximising the elegance of the installation.

In a system of micro-oxygenation, the precision and reliability of the dosage are indispensable but insufficient conditions. Oxygen, supplied in a continuous and constant mode, should be distributed to the wine in the most opportune of means until all of the supplied gas is effectively dissolved in the wine via the most homogeneous means possible.

It is here that the diffuser comes into play. Immersed a few centimetres from the base of the tank, the diffuser generates a column of fine oxygen bubbles that climb upwards, transferring the desired dose to the wine, thanks to a phenomenon of gas-liquid diffusion,.

The diffusers utilised in micro-oxygenation are of a varying nature and quality, differing in form, dimensions and materials. Generally (but not always, as we shall see further on), one deals with spargers being of a more or less porous ceramic material or of sintered steel.

There are bubbles and bubbles

plane ceramic diffuser by Parsec suitable for micro-oxygenation in barriques

The fundamental thing to bear in mind is that not all diffusers are the same. The dimensions of the microbubbles impact upon the velocity of ascent and the passage of the oxygen from within the wine in dissolved form. The key is that all the oxygen supplied by the diffuser is dissolved into the wine before the bubbles reach the surface of the liquid. In the case to the contrary, there is a risk of creating a build-up of oxygen on the surface of the wine, with the possible consequent proliferation of aerobic and filmogenic microorganisms as well as the insurgence of uncontrolled oxidation phenomena.

Some will recall how, throughout the first years after the introduction of the micro-oxygenation technique into cellars, limitations were given for the height of the tanks (generally of around 2.5 metres) within which it was possible to micro-oxygenate.

A group of researchers from the University of Bordeaux, among them Audrey Devatine and Igor Chiciuc, have studied in-depth the physics of the gas bubbles in micro-oxygenation and the dynamics of oxygen transfer to the wines.

In their research, they characterised above all the dimensions of the microbubbles produced by diffusers with differing characteristics. In accordance with the differentiating microporosity and material, the various diffusers are able to produce microbubbles with diverse dimensions and greater or lesser homogeneousness (fig. 1).

The distribution of the pores in diffusers for micro-oxygenation diverges in accordance with the material and shape (Devatine et al, “Oxygène et vin”, Parsec ed.)

In the study also published in “Oxygen et vin” (Parsec ed.), the same researchers evidenced the existent relationship between the bubble dimensions and the characteristics of the means and the dose of micro-oxygenation. The dimensions of the bubbles increase together with increments in the dose (range), just as occurs with the increase of the alcohol concentration, whilst not exerting a significant influence neither on the acidity nor the content of polyphenolic substances in the wine.

In a study published in 2009 on Chemical Engineering Science from the same Audrie Devatine and Martine Mietton-Peuchot, it was finally clarified that there exists a relationship between the column height along which the bubbles rise back up and the diameter of the pores of the diffuser. The authors went on to express this relationship in a mathematical model that considers all the factors at play, such as the characteristics of the wine like the alcohol content, the dissolved CO2 content and the progressive oxygen depletion of the bubble during its ascent towards the surface.

Simplifying the concept: the more one utilises a dosage system capable of dispensing low or very low doses as well as diffusers and materials able to produce fine bubbles, the more slowly these shall rise back up and it will be possible to apply micro-oxygenation to containers with heights less than the two and a half metres indicated by the first constructors.

One diffuser for each tank and for each application

The stainless steel and ceramic diffusers produce micro-bubbles in order to ensure the solubility of the injected oxygen.

“Experiments have explained that, which even just with our own experiences, we had verified,” explained Giuseppe Floridia, CEO of Parsec s.r.l. “The minimum height of the vessel depends on the dosage applied, the dimensions of the bubbles produced by the type of diffuser utilised, the pressure of the oxygen outflow, as well as the continuity and homogeneity of the gaseous flow. Today, Parsec offers not only a precise and reliable dosage system, but also a vast range of spargers, from which it is possible to select those best suited to the geometry of each tank and to apply micro-oxygenation also to containers with a very low drum level such as in the barriques.”

But what spargers are most suited to each application? The dimension of the bubbles depends upon the material and the adhesion force with which the bubbles in their formation are retained. Ceramic material is characterised by a lower adhesion force than steel, meaning that with an equal pore size, the bubbles produced by ceramic diffusers are finer and more homogeneous in respect of those spreading from diffusers in sintered steel. Besides the material, also the form of the sparger has an influence on the dimensions and the distribution of micro-bubbles.

“Generally, with the same characteristics of the material, the ceramic diffusers are capable of producing finer and more homogeneous bubbles,” Floridia further elaborates, “and as such, they are more suitable for the micro-oxygenation of small- and medium-sized tanks, whilst those in sintered steel can be utilised in the macro-oxygenation and micro-oxygentation of vats with greater dimensions.”

“Nonetheless, the form is also important. When the bubbles meet other bubbles along their route, they create the so-called coalescence phenomena, causing an increase in the average dimensions of the bubbles and a diminution in their homogeneity,” continues Floridia. “This occurs frequently in cylindrical spargers in which diffusion is via a vertical surface placed parallel to the pathway of the bubbles. To remedy this inconvenience, Parsec has invented flat diffusers, having a disk-like shape, whose surface is positioned horizontally. The bubbles distributed by these diffusers are homogeneous and extremely fine, being released in a column of liquid having a greater surface, further reducing the drum of liquid necessary for the application of micro-oxygenation.”

The aging of red wines is essentially an oxidative process. This has always been the case. The evolution (positive or negative) of the features of colour, flavour and astringency takes place within the cogs of one single engine: oxygen. This is irrespective of which aeration or oxygenation technique you choose, from the racking stage, to the wooden barrel up until macro and micro-oxygenation. For each wine and for each refined style, however, the oxygen has to be managed, it should neither include too much nor too little in order to avoid complications of various types.

Micro-oxygenation is a method for managing wines more accurately, in the right manner, and with the desired dose. The rest is just a question of style and choice, a tool held by the grower and the winemaker.

Criticism sometimes levied against this technique is completely unfounded: is a breadknife a harmful tool? Obviously it isn’t, however when used in its own way it is useful and requires both brains and skill (it should not be given to a child or to a serial killer).

Finally, the research world has some exciting news which will clarify some points on the how oxygen should be managed properly in the refinement of red wines.

Using the results of their studies, Boulton and Singleton, of Davis University, California, two pioneers in the study of phenolic compounds and their reactions to wine, have developed a link about the possible relationship between the quality of a wine, expressed in terms of scoring points, and the range of oxygen consumption. Whereas, of course, the ratio of oxygen/quality is dependent on the type of wine (or rather the amount of reactive polyphenols) and the range recorded takes into account all of the contributions of oxygen which the wine encounters in its lifetime (during handling, batching, oaking in wood, etc.), it has been observed that types of wines such as Sherry see their quality increase with the level of oxygen consumed, while the opposite occurs with white wines. In red, contrary to this, there is an area in which the quality grows along with the level of oxygen, this remains stationary, and then decreases. “In medium stat virtus”, while at the extremes there are faults of reduction or oxidation, but also the absence of evolution (have you heard of wines becoming “stuck” in its evolution?) or its excess.

Micro-oxygenation and respect for the style and varietal features

In red wines, the concentration of the various compounds of the phenolic profile defines the structure of a wine, whilst also giving an indication as to its oxygen requirements, and consequently the order of the level of the dosages to be taken when using the technique of micro-oxygenation.

A more structured wine will require more oxygen than another one less concentrated and more “fragile”. For this last wine lower dosages are required together with a greater focus on oxidative risk management and on any changes in its organoleptic parameters. This is true throughout every phase of its manufacturing process, not only during micro-oxygenation.

At the time when the dose is selected, it is necessary to define the purpose, and the style, for which you apply the micro-oxygenation and this is the impact desiderd for each the wine. The same thing doesn’t even happen when selecting how the oaking process works (how much and will new wood be required?) or when a clarification is sought?

A criticism sometimes advanced to micro-oxygenation is that it influences the flavour profile of the wines, standardises them and reduces the amount of variation and tipicity and is suitalbe for the sole purpose of “simply” experiencing a taste of global wines. The answer is that in fact micro-oxygenation is a tool with which you can work alongside various impacts and doses ranging from the lowest and those which most typically respect the wine, to the highest which cause the wine in question to undergo significant evolution. The remainder is largely a matter of style.

The technique of micro-oxygenation of red wines can be used in a different and in more or less invasive manner on the varietal features of the wines.

It can be used at discrete levels (for what we call low-impact) with the aim of providing the necessary amount of oxygen to the wine so that it can evolve and be maintained in a redox equilibrium which enhances the varietal characteristics of the grape even during periods of long-term aging. This is the approach adopted by Parsec from the earliest times, initially mainly for caution, and the one which over time the experience and new-found knowledge on the evolution of red wines has confirmed to be the most accurate.

The other style, which we call “high impact” on the organoleptic profile of wine is the one in which you are seeking the softening tannins and one which strives for the development of olfactory features of evolution such as plum or chocolate, even during periods of rapid aging. Of course, a legitimate choice, suitable for example in wines which need to be prepared in a short space of time, and which do not have a long shelf life when inside a bottle. It is a choice, however, which is not suitable for wines which will be subject to long-term refinements inside the bottle, and which cannot improve the varietal characteristics of the wine, as it favours an aromatic sweet, ripe, or overripe component.

The impact being sought should be clear from the outset because it influences not only the final results, but also, quite possibly, the life expectancy of the product.

A new marker for premature aging red wines

Recently, some French researchers (Dubourdieu et al., 2012) have identified an olfactory and aromatic marker which is linked to the premature aging of red wines, the so-called Premox, one which is associated with the characters described as prune, stewed fruit and dried figs. The responsible for these characters would be the γ-nonalacton and 3-methyl-2, 4 – nonane dione (MDN) and their formation would occur in oxidative conditions.

The production of the first one in particular seems to be favoured by some winemaking conditions such as the high degree of ripeness of the grapes, the low concentration of sulphur dioxide, the high pH value, and the use of wood, with higher levels (albeit lower than the perception threshold) being recognised in new barrels rather than in those during the first or second year of use.

Also related to these new findings, we can say that the approach towards micro-oxygenation is more closely linked to what we called “low impact” where in fact, in compliance with the varietal characteristics of the wine, the characters of oxidative evolution are neither called for nor achieved.

The aromatic markers of premature aging offer a new aspect when it comes to understanding the complex relationship between oxygen and wine, enhancing process control, and finally looking even further afield, at the period of aging inside a bottle, which unfortunately is often neglected.

As all the techniques the use of micro-oxygenation has seen various ages. Even the barrel, for example, has been used in previous decades in an indiscriminate way meaning that today it is used more rationally and maturely, which is a preference for the effects of technology and which does not rule out the actions of aromatic oak and roasting.

The same was also for micro-oxygenation: there was an initial moment of youthness, in which some winemakers went in search of a marked effect and a direct impact on the character of the wines. Is to that style to which are directed those criticism that in some cases have been made to the use of this technique. But now even micro-oxygenation has reached its maturity, it is a more widely known phenomenon, you have more control of oxidation and oxygen management also in other manufacturing processes, and what you want is not an enhancing technique, but a tool to help the wines to bring out their characters, and features from both their variety and their local region. Even in its infancy, however, some were less inconsiderate or reckless of others: not to be those who claime “we told you so,” but Parsec has always sustained a low impact of oxygen on wine…